Organic materials, especially paper, treated with distally perfluoroalkyl amine



United States Patent 3,378,399 ORGANIC MATERIALS, ESPECIALLY PAPER,

TREATED WITH DISTALLY PERFLUOROAL- KYL AMINE George M. Rambosek, Maplewood, Minn, assignor to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware No Drawing. Filed Apr. 13, 1964, Ser. No. 359,431

5 Claims. (Cl. 117154) ABSTRACT OF THE DISCLOSURE Compounds in which perfluoroalkyl groups and amine groups are situated at the opposite ends of a linking chain are applied as beater additives to paper pulp or as coa-tings or impregnants to paper or fabrics and are found to be substantive thereon to an extent suflicient to provide organic materials and especially papers, which are oleophobic.

This invention relates to a novel treatment to promote oleophobicity and particularly a process for the treatment of fibrous materials.

It is known from the work of others that the application to fibers of organic compounds possessing fluorochemical terminal chains promotes oleophobicity. The most satisfactory of such treatments employ polymeric materials or Werner type complexes. Such treatments of fabrics with polymeric materials provide fabrics which to a considerable extent retain water and oil resistance after dry cleaning and/or laundering. Similar treatments of fabrics with monomeric or relatively low molecular Weight materials having similar fiuorinated termini on the other hand provide fabrics possessing oleophobic properties which are lost to a greater or less extent on laundering and/or dry cleaning and in some cases may even evaporate in air. Oleophobicity is generally more or less related to the percent of fluorine associated with the fabric, that is for a given fiuorinated compound higher levels of oleophobicity are generally associated with higher levels of application. What is said with respect to fabrics would be expected to apply likewise, differing only in degree, to random webs such as paper. Such is not entirely the case, however, and the production of oleophobic papers presents problems which are not readily solved merely by application of principles learned in connection with fabrics.

One object of this invention is to provide a process for producing oleophobic paper having enduring oleophobicity.

A further object of the invention is to provide a proc ess for conferring oleophobicity on water insoluble organic materials such as fibers and dispersible particulate materials such as starches.

Yet another object of the invention is to provide oleophobic papers having resistance to liquid and semisolid organic materials such as solvents, oils, waxes, thermoplastics, asphalt, greases and the like.

A still further object of the invention is to provide a process for the production of oleophobic papers on conventional equipment.

Other objects will become apparent from the disclosure hereinafter made.

In accordance with the above and other objects of the invention it has been found that distally perfluoroalky'l amines show sufficient permanency when applied to ce1 lulosic substrates such as paper as to provide useful oleophobic papers which retain their oleophobic properties even after prolonged storage. As will be seen from the following disclosure there are many different embodiments of my invention.

3,378,399 Patented Apr. 16, 1968 In its broadest aspects my invention contemplates treatment of water insoluble organic materials with distally perfluoroalkyl amines to promote oleophobicity. In this aspect I contemplate not only paper fibers but also textile fibers, particularly materials such as starch, and also leather, wool and other solid organic materials.

The distally perfiuoroalkyl amines employed in this invention possess a perfiuoroalkyl group at one end and a primary amine group at the other end the two being connected by a divalent composite linking group consisting of at least two divalent radicals selected from the group consisting of alkylene of 2 to 12 car-hon atoms, aralykylone of 8 carbon atoms, oxa, unsubstituted aza, carbonamido, unalkylated sulfonamido and N-alkyl-sulfonamido at least one of said radicals being alkylene, not more than two of said radicals comprising amide linkages and not more than one being aralkylene, and sulfonamido groups, when present, having the sulfur atom distally located in said divalent radical to the point of attachment of the primary amine group.

A preferred class of distally perfluoro'alkyl amines for the purposes of this invention are those possessing a sulfonamide linkage, at least one aza group, not more than about 4 oxa groups and at least two alkylene groups in the composite linking group. The term sulfonamide linkage includes both alkylated and unalkylated sulfonamido groups. The members of this preferred class possess certain unusual properties in that they show a higher degree of substantivity on cellulosic and synthetic fibers than possessed by other types of distally perfluoroalkyl amines. Thus they are much more firmly bound even in the absence of any fixative as will become evident from the further disclosure herein.

Included in these preferred distally perfluoroalkvl amines are compounds of the formula:

wherein R is perfluoroalkyl of 4 to 12 carbon atoms and W is a composite linking group. Structure of W which are suitable will be seen to include:

where R is hydrogen or alkyl of 1 to 6 carbon atoms, R is alkylene of '2 to 12 carbon atoms, In is a numeral and n is a positive integer.

The numerical value of m may be zero or a positive integer and in the case of amines derived from polyethyl eneimine may be in the hundreds. It will be understood that in these cases the structure shown is intended to refer to the branched compounds as they exist and is not to be construed as limited solely to linear polyethyleneimine, although when m has values of 0 to about 8 linear structures are intended. It will also be evident from the illustrative compounds set forth hereinbelow in the examples that each R group in the molecule may be selected individually.

These distally perfluoroalkyl amines in which R is other than hydrogen are generally obtained from available carbinols by reaction of the benzene sulfonate ester with the appropriate diamine. This reaction is more fully described in the copending application of Emory Tokoli, Ser. No. 350,553, and now abandoned. Those in which R is hydrogen are available by reaction of sulfonyl fluorides with suitable amines as described in the same application. It is a significant property of many of these amines that they behave as surfactants and dissolve very readily in water, particularly in the presence of a trace of acid, to give foamy solutions.

The broad process of the invention may be carried out by padding or saturating the organic material, such as paper or fabric, with a solution of the desired distally perfiuoroalkyl primary amine (either as free base or as the salt with an acid) followed by drying for a short time. For treatment of paper with the preferred class of distally perlluoroalkyl amines application may be either as a solution which is dried, or the desired amine suitably dissolved in acidulated water may be included in the beater mix. The substantive nature of the preferred class of amines is especially shown from the fact that they are selectively removed from the very dilute solutions employed in paper making in which they may be present in concentrations of the order of thousandths of a percent or less by absorption in the raw pulp which retains the amine when cast into paper. For use in this embodiment of the invention the distally perfiuoroalkyl amine is employed in proportions such that there is from about 0.1 to about 3 percent by weight of fluorine for the dry weight of pulp. Preferably the amount is from about 0.2 to about 2 percent of the weight of pulp.

In another embodiment of the invention a hydrophilic bodying agent for textiles, particularly starch but also including, for example, polymeric materials, is dissolved or suspended in an aqueous solution of a distally per fiuoroalkyl amine. The combination of amine and starch is then employed for bodying fabrics and provides soil resistance in addition to the bodying action. The distally pertluoroalkyl amine is employed in amount sufiicient to provide about 0.05 to about 1.5 percent of fluorine in the fabric in which the starch is employed.

Although described herein particularly with respect to oleophobicity, sheet materials of the invention having sufiiciently small pore size tend to be generally organephobic; that is, they exhibit resistance to penetration by organic liquids varying largely with the viscosity and surface tension of the particular liquid. It will be noted that the oil test kit rating described hereinelsewhere actually involves organic solvents as well as oil.

The best mode presently contemplated for practicing the invention is now further illustrated by examples in which various embodiments are more particularly described.

Example 1 A series of sheets of 50 lb. unbleached unsized kraft paper is treated by the process of the invention employing dilute acidulated aqueous solutions of distally perfiuoroalkyl amines. In each case the sheet is immersed in the solution for sufiicient time to be thoroughly wetted and then is removed, squeezed between rollers so that the weight of retained solution substantially equals the weight of the dry sheet and the wet sheet is then dried at 230 F. in a Williams Sheet drier. Equipment is thoroughly cleaned between individual treatments to avoid carryover of one treating agent to the next. The concentrations of solutions in weight percent will be seen to correspond approximately to the weight percent of amine in the final dried paper and these concentrations are selected so that the final dried paper will contain from about 0.01 to about 2 percent of fluorine in combined form. It is preferred that combined fluorine be at least 0.05 percent.

The following distally perfluoroalkyl amines, designated by letters for convenience in reference, are employed in treatment of paper as described above:

Each sheet is tested and found to possess resistance to oil penetration by means of an oil test kit. The oil test kit consists of ten solutions of castor oil diluted with a mixture of equal volumes of toluene and heptane at increasing amounts and two further solutions having no castor oil and containing only heptane and toluene. The rating is the number of the highest numbered solution which fails to penetrate the test sample when applied for 15 seconds. Penetration is shown by a pronounced darkening of the test piece. Ordinary paper is usually penetrated almost instantaneously and rates Zero. The above sheets show ratings well above zero. It will be noted that different ratings may be obtained on the two sides of a sheet, apparently as a result of the manner in which the paper is made.

The volume percents of the several solutions are shown in the following table:

Solution Castor oil Toluene Heptane Number Certain sheets are tested both fiat and creased for resistance to penetration by lard oil (a typical glyceride fatty oil) employing this oil in place of turpentine in TAPPI grease resistance test T-454 11144 which is further modified by including a weight (as in test JAN-B 121) atop the sand pile to assure contact with the backing sheet. The test is terminated at seven days. The times shown in the following table indicate the extent of holdout. Holdout to a mineral oil is normally even better.

Amine level Resistance Sheet (percent wt. of Flat Greased 1.38 Ca. 8 hrs 0.15 7 days. 0.42 Do. 0. 45 D0. 0.88 D0. 0.86 Do. 0.30 D0. 0.60 Do. 0. 36 3 days.. 0.5 hrs. 0.60 7 days 1 day.

*N-ethyl perfluoroctanesulfonamtdopolyethylenlmine where n represents a large number as described herein above.

It is evident that these papers show holdout of oil for very significant times. Paper similarly treated with 1,1- dihydroperfiuorohexyl amine shows holdout only when tested immediately and without heating during drying. The above papers show oleophobicity when tested even after prolonged storage showing that they are permanently oleophobic.

Example 2 Specimens of synthetic fiber textiles are impregnated with solutions of fluorinated amines and dried and then rated for resistance to oils by the oil test kit.

The amines which are employed are:

Amine III is a tertiary amine employed as a control to show the superiority of the process of the invention employing the primary amines I and II.

Three pieces each of' an approximately 5 oz. plain weave polyethylene terephthalate fabric and of an approximately 3 oz. plain weave nylon fabric are impregnated with 1 percent solutions of the respective three amines, air dried and heat treated at 250 F. for 15 minutes. The samples are then rated using the oil test kit described above. Each specimen is then washed for 5 minutes in water containing laundry detergent at 35 to 40 C. rinsed with clear water, dried at room temperature and again rated. The washing cycle is repeated on the polyester fabric and each specimen is again rated. The ratings are shown in the following table:

Polyester Polyamide Amine Original Washed 2nd wash Original Washed It will be seen that amines I and II provide excellent resistance even after two launderings whereas the tertiary amine III is washed out in laundering although it provides good oil resistance before laundering.

Example 3 Distally perfluoroalkyl amines of the preferred class of sulfonmides (A, B, C, H, I, K, M, O, P and Q of Example 1) are employed as beater additives by adding 1 to 2 percent acidulated aqueous solutions of each to kraft pulps beaten to Canadian Standard freeness of 500:15 at 0.3 percent concentration. The amount of added solution is determined so as to correspond to the amount of amine necessary, if completely absorbed, to give at least about 0.20 percent of fluorine in the pulp based on dried pulp (weight of amine of about 0.4 percent to about 8 percent of the weight of pulp). Handsheets are made in a 12 x 12 sheet mold (7 g. of dry pulp equivalent to a basis weight of 50 lbs. for 500 sheets 24" x 36"), pressed and dried on Williams Sheet drier at 230 F. This procedure, except for drying, is generally that of TAPPI procedure T205 m-53.

Each of these sheets is found to be oleophobic in the above described oil test kit rating procedure. Resistance to oil wicking, tested as described in US. Patent 3,109- 769, is found to be excellent. Certain sheets are tested flat and creased as described above in Example 1 for resistance to penetration by lard oil as shown in the following table:

Amine level Amine (percent wt. of IIoldout Flat Holdout Crease dried pulp) 7. 8 0.6 7 days. 0. 88 0.5 hours. 1.0 7 days. 0. 5 D0. 0. 93 1. 3 7 days. D0. 1. 2 4 hours 0. 60 12 hours 0.5 7days...

1 On one side of paper with motor oil.

Example 4 A soil repellant fabric treating solution is obtained by dissolving instant starch (of the commonly available type which disperses readily in hot water) in a 0.5 percent aqueous solution of the N-ethyl perfluorooctanesulfonamide of diethylene triamine in the proportions prescribed for use with water. The solution is employed for the starching of clothing and other articles of apparel, draperies and other textiles by the usual procedures. Comparison tests of the several articles, e.g. wearing of apparel, normal use of draperies, et-c., show that articles starched with the starch prepared as above are less readily soiled and tend to shed dust and dirt more readily than the same type of article starched with the same starch to which the amine is not added. Oil test kit ratings of fabric thus treated show values of about 4 which is considered suitable for stain and soil resistance. It will be apparent that this procedure is adaptable to home treatment of household articles and wearing apparel. Surprisingly it is found that dissolving a distally perfiuoroalkyl amine in a previously prepared solution of starch provides substantially no effectiveness.

What is claimed is:

1. As an article of manufacture a web of fibrous material uniformly permeated with distally perfiuoroalkyl amine consisting of perfluoroalkyl group at one end, primary amine group at the other end and a divalent composite linking group therebetween consisting of at least two divalent radicals selected from the group consisting of alkylene of 2 to 12 carbon atoms, aralkylene of 8 carbon atoms, oxa, unsubstituted aza, carbonamido, unalkylated sulfonamido and N-alkyl-sulfonamido at least one of said radicals being alkylene, not more than two of said radicals comprising amide linkages and not more than one being aralkylene, and sulfonamido groups, when present, having the sulfur atom distally located in said divalent radical to the point of attachment of the primary amine group.

2. An article of manufacture according to claim 1 wherein the fibrous material is a woven web.

3. An article of manufacture according to claim 1 wherein the fibrous material is paper.

4. An article of manufacture according to claim 3 wherein paper is uniformly permeated with monoperfiuorooctanesulfonamide of die-thylene triamine.

5. The article of claim 1 which fibrous material is permeated with said distally perfluoroalkylamine in the form of a solution with starch.

References Cited UNITED STATES PATENTS 2,727,923 12/1955 Husted 117-154 X 2,759,019 8/1956 Brown et al. 117154 X 2,809,990 10/1957 Brown 117154 X 2,915,554 12/1959 Ahlbrecht et al. 117-154 X 3,078,245 2/ 1963 Heine. 3,274,244 9/1966 Mackenzie 162158 X MURRAY KATZ, Primary Examiner. WILLIAM D. MARTIN, Examiner. M. LUSIGNAN, Assistant Examiner. 

